doc.: ieee 802.11-12/1104r2 submission 11ah interframe spacing values date: 2012-09-17 authors:...
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doc.: IEEE 802.11-12/1104r2
Submission
11ah Interframe Spacing Values
Date: 2012-09-17
Authors:
September 2012
Tevfik Yucek, Qualcomm Inc.Slide 1
Name Affiliations Address Phone email Tevfik Yucek Qualcomm Inc +1 408 5074286 [email protected]
Harya Wicaksana Panasonic R&D center Singapore
Blk1022 Tai Seng Ave #06-3530 Singapore
+65-65505347 [email protected]
Rojan Chitrakar Panasonic R&D center Singapore [email protected]
nic.com
Ken Mori Panasonic Corp [email protected]
Hongyuan Zhang Marvell [email protected]
Sudhir Srinivasa Marvell [email protected]
Yong Liu Marvell [email protected]
Eldad Perahia Intel Corp. [email protected]
Shahrnaz Azizi Intel Corp. [email protected]
Tom Tetzlaff Intel Corp. [email protected]
Thomas Kenney Intel Corp. [email protected]
Yongho Seok LG Electronics LG R&D Complex Anyang-Shi, Kyungki-Do, Korea
+82-31-450-1947 [email protected]
Jinsoo Choi LG Electronics
Jeongki Kim LG Electronics
doc.: IEEE 802.11-12/1104r2
Submission
Authors:
September 2012
Tevfik Yucek, Qualcomm Inc.Slide 2
Name Affiliations Address Phone email Sameer Vermani Qualcomm
Eugene Baik Qualcomm
Lin Yang Qualcomm
Hemanth Sampath Qualcomm
Richard Van Nee Qualcomm
Allert Van Zelst Qualcomm
VK Jones Qualcomm
Sun, Bo ZTE [email protected]
Lv, Kaiying ZTE [email protected]
Huai-Rong Shao Samsung [email protected]
Chiu Ngo Samsung [email protected]
Minho Cheong ETRI 138 Gajeongno, Yuseong-gu, Dajeon, Korea
+82 42 860 5635 [email protected]
Jae Seung Lee ETRI [email protected]
Hyoungjin Kwon ETRI [email protected]
Heejung Yu ETRI [email protected]
Jaewoo Park ETRI [email protected]
Sok-kyu Lee ETRI [email protected]
Sayantan Choudhury Nokia
Taejoon Kim Nokia
Klaus Doppler Nokia
doc.: IEEE 802.11-12/1104r2
Submission
Authors:
September 2012
Tevfik Yucek, Qualcomm Inc.Slide 3
Name Affiliations Address Phone email Zander Lei I2R 1 Fusionopolis Way, #21-01
Connexis Tower, Singapore 138632
+65-6408 2000 [email protected]
Li Chia Choo I2R [email protected]
Zhou Yuan I2R [email protected]
Sumei Sun I2R [email protected]
Ser Wah Oh I2R [email protected]
George Calcev Huawei Rolling Meadows, IL USA
Osama Aboul Magd Huawei [email protected]
Young Hoon Kwon Huawei [email protected]
Betty Zhao Huawei [email protected]
David Yangxun Huawei [email protected]
Bin Zhen Huawei [email protected]
ChaoChun Wang MediaTek [email protected]
James Wang MediaTek [email protected]
Jianhan Liu MediaTek [email protected]
Vish Ponnampalam MediaTek [email protected]
James Yee MediaTek [email protected]
Thomas Pare MediaTek [email protected]
Kiran Uln MediaTek [email protected]
Ron Porat Broadcom
Nihar Jindal Broadcom
Vinko Erceg Broadcom
doc.: IEEE 802.11-12/1104r2
Submission
Introduction
• SIFS time and slot duration are important keeping the overhead small [1]
• We investigate the components that makes up SIFS and Slot durations and propose values that are suitable for 802.11ah
September 2012
Tevfik Yucek, Qualcomm Inc.Slide 4
doc.: IEEE 802.11-12/1104r2
Submission
Definitions
Slide 5 Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
Definitions
• SIFSTime = aRxRFDelay + aRxPLCPDelay + aMACProcessingDelay + aRxTxTurnaroundTime.
• SlotTime = aCCATime + aRxTxTurnaroundTime + aAirPropagationTime+ aMACProcessingDelay
Slide 6 Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
Values• aAirPropagationTime
– Twice the propagation time (in microseconds) for a signal to cross the maximum distance between the most distant allowable STAs that are slot synchronized.
– Assuming 300 and 900 meters range for 11n/ac and 11ah respectively, corresponding values are 2us and 6us.
• aRxPLCPDelay, aMACProcessingDelay, aTxPLCPDelay– These are digital processing delays and depend on the digital clock rate. Assuming 11n/ac
baseband is downclocked by 10, values need to be increased by 10.– MAC processing time / TxPLCPDelay for Slot is set to zero since the MAC calculation
can be done before transmission.
• aTxRampOnTime and aRxTxSwitchTime are assumed to be the same for 11n/ac and 11ah
• aTxRFDelay and aRxRFDelay– Assuming the same filter order, delay increases 10x due to 10x bandwidth scaling (2MHz
vs. 20MHz).– We assume 1MHz will use the same filter with 2MHz mode. If narrower filters are used,
we assume smaller digital delay of 1MHz will compensate the longer filter delay.Slide 7 Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
CCA Time: Theoretical considerations
• Due to 20x BW reduction, CCA time needs to be increased 20x compared to 11n/ac– For same SNR, 1MHz STF requires 2x the integration time of
2MHz (less number of samples per symbol).
• Furthermore, to improve the detection to an SNR supported by Rep2 packets, CCA time needs to be increased by 2– Required SNR is 3dB lower for MCS0 rep2
• However, STFs are power boosted by 3dB for rep2• This results in theoretical value of 4*20*2/2 = 80us CCA
duration
Slide 8 Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
CCA Time: Practical requirements
• 10% PER point for MCS0-Rep2 requires >8dB SNR at Urban Macro channel model
• Figures in the next page shows the ROC curves for detecting valid PPDU transmissions in– 11dB STF-SNR in SCM Urban Macro channel model– 0dB STF-SNR in AWGN channel– 3dB STF-SNR in AWGN channel
• Simple correlation algorithm based on STFs is used• It is possible to meet the 90% detection requirement using
40us CCA duration for both bases (fading and AWGN).– Values less then 40us can be used. However, 40us gives some room in
implementation error. For example, a single detection threshold is used across different channel conditions.
Slide 9 Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
CCA Results – Urban Macro
Slide 10
0 0.02 0.04 0.06 0.08 0.10.95
0.955
0.96
0.965
0.97
0.975
0.98
0.985
0.99
0.995
1
FA probability
Po
sitiv
e d
ete
ct p
rob
ab
ility
BW=1MHz, SNR=11dB, Urban Macro
20us22us24us26us28us30us32us34us36us38us40us
Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
CCA Results – AWGN
Slide 11
0 0.005 0.01 0.015 0.020.9
0.91
0.92
0.93
0.94
0.95
0.96
0.97
0.98
0.99
1
FA probability
Po
sitiv
e d
ete
ct p
rob
ab
ility
BW=1MHz, SNR=0dB, AWGN
20us22us24us26us28us30us32us34us36us38us40us
Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
CCA Results – AWGN
Slide 12
0 0.005 0.01 0.015 0.020.9
0.91
0.92
0.93
0.94
0.95
0.96
0.97
0.98
0.99
1
FA probability
Po
sitiv
e d
ete
ct p
rob
ab
ility
BW=1MHz, SNR=3dB, AWGN
20us22us24us26us28us30us32us34us36us38us40us
0 0.5 1 1.5 2
x 10-3
0.95
0.955
0.96
0.965
0.97
0.975
0.98
0.985
0.99
0.995
1
FA probability
Po
sitiv
e d
ete
ct p
rob
ab
ility
BW=1MHz, SNR=3dB, AWGN
Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
Slot Time
Slide 13
11ac 11ah
CCA Time 4 40
Air Propagation Time 2 6
aMACProcessingDelay 1 0
aRxTxTurnaroundTime (aTxPLCPDelay+aRxTxSwitchTime+aTxRampOnTime+aTxRFDelay
2 (1, 0.25, 0.25, 0.5)
5.5 (0+0.25+0.25+5)
SlotTime 9 51.5 52
Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
SIFS
Slide 14
11n/ac 11ah
aRxRFDelay .5 5
aRxPLCPDelay 12.5 125
aMACProcessingDelay 1 10
aRxTxTurnaroundTime (aTxPLCPDelay+aRxTxSwitchTime+aTxRampOnTime+aTxRFDelay
2 (1, 0.25, 0.25, 0.5)
15.5 (10+0.25+0.25+5)
SIFS 16 155.5 156
Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
SIFS: Multiple of symbol duration
• We propose to use 160us SIFS time which is a multiple of 40us symbol duration (normal GI)
• This is less efficient but it would allow to the NAV to be expressed in terms of symbol duration, allowing for compressed representation of Duration/NAV field in MAC/PHY fields.
• If any transmission in a TXOP uses short GI, the duration defined by 40us unit might be slightly longer than the actual transmission sequence, but the difference is less than 1 symbol; which should not cause big impact
• Note that 11ac short GI has similar issue
September 2012
Tevfik Yucek, Qualcomm Inc.Slide 15
doc.: IEEE 802.11-12/1104r2
Submission
Pre-motion
• Do you support the following proposed interframe spacing related values– SIFS=160us, – Slot time=52us– aCCATime = 40us– aAirPropagationTime = 6us
– Yes:– No:– ABS:
Slide 16 Tevfik Yucek, Qualcomm Inc.
doc.: IEEE 802.11-12/1104r2
Submission
References
• [1] IEEE 11-12-0362, On the 802.11ah Performance
Slide 17 Tevfik Yucek, Qualcomm Inc.